How to Understand Heating, Cooling and Ventilation (HVAC)

To keep most people in first world countries comfortable, you need at least two things: an enclosure to hang onto heated or cooled air, and an engine to make the air that way. ALWAYS FIRST: create an enclosure at is relatively airtight and insulated. Now for the engine: the HVAC- air conditioner, furnace, heat pump, etc.

The question is: how much heating or cooling should I install in this home so it’s both very comfortable and cost-effective?

Great question! There are very precise calculations for this (spelled out in ASHRAE Fundamentals and in Manual J from the Air Conditioning Contractors of America. You take detailed information about weaknesses in the home’s enclosure (window size and orientation, how much air leakage exists, etc) and put it into a computer.

Doing an HVAC load calculation by hand isn’t good enough in most homes because you need an hour-by-hour look at the effect of the sun and weather on the home. This calculation gives you a very specific amount of heating and cooling that a home needs. You don’t need to add anything to this, because the calculations were written by engineers, who are very cautious and conservative people-they’ve added all the safety margins already to make sure you’ll be comfortable.

Next question: how are we going to deliver the warm or cool air evenly everywhere in my home? Wow, that’s a great question! Guess what? There’s a calculation for that!

Again, ASHRAE Fundamentals or Manual D will tell you exactly how the ducts should be designed and installed so that every single room feels comfortable and refreshing, which is possible for every home, in every place, new and old alike.

Now that we know exactly how much heating and cooling each home needs, we have to buy an engine that can make it. Here’s where most people make a big mistake: they buy an engine that’s too big. These people may think that they need a little extra power for when the weather is really crazy. In fact, many of my clients have twice as much machinery as their home actually needs. That’s like building an escalator and installing a V8 engine to run it- it takes you where you need to be super fast, but it’s also uncomfortable, really loud, and slightly nauseating. So you pick an air conditioner, furnace, or heat pump that fits the home like a tailored suit.

Last step: we test the tightness of the duct system. A duct system is plumbing for air- you do not want it leaking. You might think if the ducts are all inside the envelope and they leak air here or there, it’s not such a big deal. It IS a big deal, and here’s why:

If we spent time and energy calculating exactly how much heating and cooling this home needs, exactly how the duct system needs to be designed and installed, and picked out the perfect heat pump or furnace, all of that gets flushed down the toilet if the conditioned air doesn’t actually go to the rooms where you need it!

Proof Is Possible, and careful planning and performance testing are the keys. Your home won’t need rescuing if you do it right the first time.

PODCAST #53 A/C CAN BE SEXY: Kristof Irwin on the Magic of Variable Refrigerant Capacity

Today we talk with Kristof "Handsome" Irwin, founder of Positive Energy in Austin Texas, about why your air conditioner is probably an idiot (bless its heart) and HVAC heaven that you might not have heard about.

To download this episode or hear more, subscribe in iTunes or visit BuildingPerformancePodcast.com

PODCAST #52 NOT YOUR GRAMMA'S BUILDING SCIENTIST: Iain Walker on air tightness, testing, and the origin of stinkiness

Today we talk with Dr. Iain Walker of Lawrence Berkeley National Laboratory about the frontier of air tightness, fresh air ventilation, and why we're arguing about it in the first place.

To download this episode or hear more, subscribe in iTunes or visit BuildingPerformancePodcast.com

Most 'Experts' Got It Wrong: Ice Dam Roof Damage is Not an Insulation Problem

Despite good intentions, most media coverage on ice dams is misguided, and can actually make problems worse

MARCH 11 2014 – CHICAGO – This winter has been a record-breaker, but few homeowners know what they can do about it. Roof snowmelt re-freezing at the eaves (called ‘ice dams’) is a problem for many homes. It causes structural damage to roofs and walls every winter. And with more snow on the way, the immediate question is, what can a homeowner do about it?

Misguided sources, including home improvement shows and news networks, say that ice dams are made when hot air escapes from the home into the attic because of missing insulation, and artificially warms the roof. This is only half right– since warm air rises, it does indeed push up through the ceiling, into the attic or roof cavity, but insulation cannot, and does not, fix air leakage. The only thing that can fix air leakage is airtight materials, which insulation is not.

Consider your furnace filter, for example: air goes right through it, and filters out particles that could damage the furnace or air conditioner… AND it’s made from fiberglass, just like insulation. So really, the air that pushes out of your home into your attic will be the cleanest air in the whole house, if you have a well-insulated attic. But the big problem remains; warm air will still leak out.

Solving ice dams once and for all with Air Sealing is the only solution. Luckily this is very affordable, needs no maintenance or replacement, and doesn’t consume energy (unlike the ridiculous heat wires you can string along your eaves as a band-aid). Never install more attic ventilation before the attic floor is air sealed- this just accelerates the leakage of air from the house to outdoors. And never add more insulation before air sealing- this only makes the attic colder, so the warm air leaking into it condenses everywhere, which can lead to mold. Hire a Home Performance Contractor for air sealing, not just any contractor. Home Performance Contractors test before and after their work with a blower door, to prove you got what you paid for, and to prove that the problem is actually solved. The best part of Home Performance is that proof is possible.

Smart homeowners are opting for a comprehensive home analysis with performance testing, before investing in improving any part of their home. This ensures that home improvements are prioritized, cost effective, and that each improvement makes the home more comfortable, durable, healthy, and energy efficient. It also ensures that you never flush money down the drain guessing at fixes. See the Home Diagnosis Guide to Finding Home Performance Pros to locate help in your area.

PODCAST #51 WHAT GREEN'S REALLY WORTH: Appraisal Expert Sandra Adomatis on The Bottom Line

Today we talk with Sandra Adomatis, Appraisal Institute's green valuation expert and author of Residential Green Valuation Tools, about greening the MLS, swimming pool ROI, and the future of appraiser apprenticeship (which, yikes).

To download this episode or hear more, subscribe in iTunes or visit BuildingPerformancePodcast.com

PODCAST #50 WEST SIDE, BABY! A Bunch of Californian Rockstars Show Us What's Behind the Curtain

IT'S A PARTY! Today we talk about the universe of home performance in California with:

• Dan Perunko & Gavin Healy of Balance Point Home Performance
• Mike MacFarland & Brian Tyrrell of Energy Docs
• Natalie Freidberg & Scott Nyborg of Home-ology
• Caroline Veerman of Loisos Design
• and Judy Rachel of Green Achers Sustainable Solutions (that spells GASS, but she doesn't care- she's Judy Rachel!)

To download this episode or hear more, subscribe in iTunes or visit BuildingPerformancePodcast.com

PODCAST #49 THIS HOUSE SUCKS, BUT NOT VERY HARD: Brett Singer, scientist, shows us where depressurization testing has led us astray

Today we talk with Brett Singer, air quality scientist at Lawrence Berkeley National Laboratory, about the red herring of worst-case depressurization on combustion testing, and the actual hidden enemy in every home.

To download this episode or hear more, subscribe in iTunes or visit BuildingPerformancePodcast.com

PODCAST #48 PRODUCTS WILL SAVE US: Keith Aldridge on Future Solutions in Stuff

Today we talk with Keith Aldridge, VP of Business Development for Advanced Energy, on what the programs get wrong, why human QA will disappear, and what your clients really want. Recorded at the ACI Regional Home Performance Conference in San Diego, CA.

To download this episode or hear more, subscribe in iTunes or visit BuildingPerformancePodcast.com

Passive House Explained in 90 Seconds

This video’s not one of ours, but we love it so much! If you’ve heard of Passive House (or Passivhaus) building certification, this entertaining little video breaks it down nicely! Since I just became one of the first Passive House Raters in the Midwest, we hope to be doing more and more passive construction projects soon.

Passive House Explained in 90 Seconds from Hans-Jörn Eich on Vimeo. Thanks to Hans for creating this Passive House video!

I'm a Passive House enthusiast. I'm involved in this great movement to create highly energy efficient buildings that use 80 to 90% less energy. But how? I get asked often what a Passive House is. This is the low down in 90 seconds.

PODCAST #47 BIG SEXY MORTGAGES: Kerry Langley on How to Borrow More, Lend More, and Keep More with Energy Efficient Mortgages

Today we talk with Kerry Langley of Synovus Mortgage about how his company collaborated with Southeastern builders, HERS raters, and homebuyers to make an absolute killing for everyone involved. Corbett: "Why hasn't everyone been lending money this way?" Kerry: "I have absolutely no idea." YOU NEED TO HEAR THIS.

To download this episode or hear more, subscribe in iTunes or visit BuildingPerformancePodcast.com

New BPI Exam Prep Promises Higher Certification Rate

July 12, 2013 – Chicago – Standards for the home improvement industry have been given another push up the ladder with the launch of BPIexamprep.com . The online training, from Home Performance Diagnostics author Corbett Lunsford, is designed as a supplement to BPI Training or for professionals who need to self-study due to limited time, budget, or access to training.

Homeowners and government programs alike have been demanding a growing army of BPI Certified contractors , and even building codes are now recognizing the certification for new home quality control. "BPIexamprep.com has been years in the making, and something I wish I’d had when I was getting ready to challenge these certification exams," says Lunsford. The modular, self-paced video course offers students all the information needed to put the finishing touches on preparation for any of the main five BPI Certification exams: Building Analyst, Envelope Professional, Heating Professional, A/C and Heat Pump Professional, or Multifamily Building Analyst.

While BPI Exam Prep is not meant to take the place of a week-long hands-on BPI Training, it does help students pass the exams the first time. Many people who seek BPI certification have been out of school, and out of the habit of test-taking, for years. "BPI exam sets have a standard price of $750, so it can be expensive to have to re-take these tests," laments Lunsford. "I got sick of watching other school’s students fail these exams on their first try, simply because they didn’t know what to expect. The psychology of test-taking is a huge hurdle, and this course helps students get over it."

The online course is self-paced, interactive, and includes 6 modules: 5 guidance videos from Lunsford and a 100-question practice BPI exam. After having trained hundreds of BPI Certified Professionals, and proctored hundreds of BPI exams, Lunsford and his Building Performance Workshop are standing up for students everywhere, and giving them the edge they need to ace the test.

FOR A FREE, INTERACTIVE VIDEO GUIDE TO BPI CERTIFICATIONS, OR TO GET A TOUR OF THE COURSE, VISIT:
http://bpiexamprep.com

Ventilate it right, and Ventilate it Right. Did I say Ventilate?

We recently ordered ourselves a copy of the new ASHRAE 62.2-2013 standard and today I spent some time sifting through the madness.

In Illinois, this is becoming a pretty regular topic of discussion since all new construction requires mechanical ventilation. Plenty of our clients are still using exhaust only ventilation under the 62.2-2010 standard, but as Joe Lstiburek pointed out in this article, it doesn’t always work as planned. And as an energy modeler, I personally know that designers who use exhaust only ventilation with the new standard are going to be hit hard with some serious energy penalties from the increased rates. While this is not meant to be totally encompassing, here is a quick synopsis:

• Mechanical vent rates have been increased to a total ventilation base model of  7.5cfm( Bedrooms+1) + 0.03cfm(Floor Area) and no longer assume default leakage of 2cfm/100ft^2
• In order to take credit for infiltration, a blower door must be performed, and Effective leakage area, Normalized leakage, and effective annual average infiltration rate must be calculated. The required mechanical ventilation rate is the difference from the total ventilation and the effective annual average infiltration rate [the effective annual average infiltration rate must be NO GREATER than 2/3 of the total ventilation rate]
• 2013 standard assumes no ‘reasonable’ leakage in multifamily buildings
• CO alarms are now required in all dwelling units
• Similar to previous standards, does not address unvented combustion sources, material off-gassing, smoking, etc…
• Thermal comfort not considered in ventilation strategies
• Ventilation rates must be measured and net ventilation must meet the required ventilation
• When atmospheric OR solid fuel burning appliances are within pressure boundary, the net sum of the two largest exhaust fans must not exceed 15cfm/100ft2. If this occurs, capacity must be reduced or outdoor air must be introduced.
• Ducts/air handlers outside the envelope must be sealed to reduce leakage to a rate of 6% of total airflow when tested at 25Pa
• Mechanical systems that supply air though 10 or more feet of ductwork AND through a thermal conditioning component require a minimum MERV 6 filter
• Multifamily dwelling units must meet the total ventilation rates of a single family home, with no credit for infiltration
• Corridors and common areas of multifamily buildings must be ventilated to 0.06cfm(Floor Area)
• Existing building shall be ventilated to the total ventilation as described above and no credit for infiltration may be used unless it is tested. If the credit for infiltration is greater than the total required ventilation, no ventilation is required.

In short, what this says to me is that all buildings need to be tested with a blower door to take advantage of the infiltration credit, and that all ventilation systems should be balanced (meaning supply outdoor air = exhaust air) with heat/enthalpy recovery systems. If you on the ground trying to collect all the dropped HERS points you can, you may just have to make some changes to your ventilation design in order to do so. Luckily, blower doors are required in our state already – but calculating that infiltration credit is something that will cause most designers to pull their hair out…